Thermal cut-out



5 Sheets-Sheet l -& \AMMX,

f'z ven'zons: flag/z a l. Pip 16%,

5 igwrdj Zirzdel&

Oct. 25, 1938. H. A. TRIPLETT ET AL THERMAL CUT-OUT Filed April 25, 1934 Oct. 25, 1938. H. A. TRIPLETT ET AL THERMAL CUT -OUT Filed April 25, 1934 5 Sheets-Sheet 3 Int/972M51- WM.

Z2 FZpZeZz, rclflindell.

Oct. 25, 1938. H, A. TRIPLETT ET AL THERMAL CUT OUT Filed April 25, 1934 5 Sheets-Sheet 5 Patented, Oct. 25, 1938 UNITED STATES PATENT OFFICE mamas CUT-OUT I s n n A. 'lri'plett, Wilmette, and sum-a r. Hndell, Chicago, 111., assignors to Schweitzer a Conrad,

Inc., Chicago, 111., a corporation of Delaware Application April 25, 1934, Serial No. 722,280 41 Claims. (01. 200-142) The present invention relates to thermal pro- I tection of transformers and the like. Whereas thguspecificdisclosure relates to the protection of gh tension transformers of the potential type,

5 it is to be understood that the invention is not limited to any particular type or voltage of transformer, nor in fact is the invention to be limited to the protection of transformers only. Certain features and combinations herein disclosed are m applicable to the same or analogous service in other equipment or apparatus.

In known transformer installations, fuses and circuit breakers on the high tension side are-at present employed for the twofold purpose of first l5 protecting service in the event of a transformer winding or bushing failure, and, second, protecting the transformer from the thermal efi'ects of a short circuit or overload occurring on the load side of the transformer.

20 A condition of partial breakdown may occur in a transformer. This may arise through breakdown of the insulation between adjacent turns occurring, for example, inthe high tension winding. The primaryfuse or circuit breaker will not operate if the current drawn does not exceed the rating of the fuse or circuit breaker. That is to say, the actual current flowing may not exceed the rating of the transformer, but the heat generated in the short circuited coil is localized and 30 may be very considerable. This heat is imparted to the oil, raising it to the flash point. The fault tends to proceed to the short circuitstage because the heating tends to destroy theinsulation. Arclng which occurs at the instant of final break- 35 down is capable of igniting the oil vapors, resulting in an explosion and fire. This is a hazard to life and property, which the fuse or circuit breaker of commercial type is incapable of preventing. To avoid explosions from such causes,

the transformer must be disconnected before the temperature of the oil is raised to the flash point.

The present invention aims to provide a novel circuit interrupter provided with controlling means, and organized to interrupt the circuit 45 when the temperature of the oil of the transformer or the like exceeds a predetermined value.

We are aware that it has heretofore been proposed to provide a thermal control for a conventional circuit breaker. Such a circuit breaker may also be controlled by excess current fiow, or

be hand controlled.

The preferred form of the present invention aims, however, to provide a simplified and com pact form of circuit interrupter which shall be 56 not only less expensive than conventional forms of circuit breakers, particular service. The present invention is particularly concerned with a compact circuit interrupter of the single operation type intended to be enclosed either within the transformer shell or in a separate housing and to be controlled by the temperature of the transformer oil.

In the copending application of Beckett and Lindell; Serial No. 721,706, died April 21, 1934, there is disclosed a form of thermally controlled circuit interrupter adapted to be disposed in thermal contact with the oil and disposed in the transformer casing, and being of the shop reloadable type.

The present invention aims to improve the aforesaid device and devices of the aforesaid class or type. V

One of the chief objects of the present invention is to provide a device of this class or type h the features of thermal control and of circuit interruption individually organized to a highbut better adapted to the er degree, and so coordinated as to ensure reliability and certainty of operation at the desired temperature and with adequate interrupting capacity to withstand service requirements.

Another object of the invention is to provide a circuit interrupter wherein the contacts of the device are releasable by external means, preferably mechanical in character and applied or positioned exterior to the assembly of the interrupter.

. A further object ofthe invention is to provide a sealed interrupter unit having automatically separable contacts locked in engagement with a separate thermal element with a mechanical transmission of motion to unlock or release the contacts for automatic separation. The thermal element may be remotely situated, if desired.

The transmission, instead of being mechanical,

may be a fluid pressure transmission, or an electric transmission, but, in any case, the unlocking or release of the contacts is effected by an externally applied thermal element assembly, and without unsealing the interrupter unit. I

A further object of the invention is the provision of a power element which is applied under control of the thermal element to the unlocking or release of the automatically separable contacts. Preferably, this power element is a spring which has two stages of motion, the first stage ensuring the complete release of the thermally controlled element, and the second stage unlocking or releasing the contacts. the two phases of operation By this provision, are separated to avoid interference of one with the other, and it permits of delivering a blow or thrust to the release means after complete release from possibility of thermal change or other factor interfering with full actuation of the thermallycontrolled means. A

Another object of the invention is to provide a thermally controlled circuit interrupter of great sensitivity and deflniteness of operation, and of great interrupting capacity in small space.

Another object is to provide a thermal actuating mechanism capable of rapid response to temperature changes in the circum-ambient medium.

Another object is to provide means under thermal control for simultaneous control of the actuationof a plurality of circuit interrupters.

A further object is to provide a novel form of automatic circuit interrupter of high interrupting capacity in small space and arranged for mechanical release all in a fluid tight housing.

Such'a circuit interrupter may be submerged in oil and housed in a metal casing without eflect upon its interrupting capacity.

A further object of the invention is to provide a suitable organization of interrupter and thermal control with a mechanical transmission allowing separation and separate housing of the interrupter and the element. a I

A further object of the invention is to provide acircuit interrupting device either for individual operation or gang operation, which may be controlled by any selected phenomenon. The circuit interrupter-mechanism, with its necessary structure and environment for operation, and suitable governing mechanism providing control at a large mechanical advantage, may advantageously be employed wherever the controlling phenomenon, or its responsive element, is designed to produce or provide only a small operating force. Thus, for example, the circuit interrupter with its detent, operating mechanism therefor, and control mechanism therefor, might be governed by a pressure sensitive element, instead of a thermally sensitive element. Or it might be controlled-by an element responsive to any other desired or selected phenomenon, either automatically or under hand control.

Other andfurther objects of the invention will become apparent from the following specification, drawings and claims.

Now in order to acquaint those skilled in the art with the manner of constructing and operatinga device embodying our invention, we shall describe, in conjunction with the' accompanying drawings, a specific embodiment of the invention.

In the drawings: Figure 1 is a vertical longitudinal section through one embodiment of our invention;

Figure 2 is a front elevational view of thecircuit interrupter shown in Figure 1; m

Figure 3 is a fragmentary vertical section through the thermally sensitive element and the interrupter contact, on an enlarged scale;

Figure 4 is a transverse section through the clutch element and movable contact, substantially on the line 4-4 of Figure 3;

Figure 5 is a side elevational view, partly in section, of the thermally sensitive element and the leverage system for providing a mechanical advantage: v v v Figure 6 is a top plan'view of the element shown in Figure 5;

Figure 7 is a vertical section, partly in elevation, of the circuit interrupter installed in a different manner from that shown in Figure 1;

Figure 8 is a longitudinal section, on an enlarged I rupters are employed;

. Figure 10 is a side elevational view of the tripping spring mechanism and the release therefor; and

Figure 11 is a fragmentary cross sectional view taken on the line ll-"-ll of Figure 10, showing one of the spring actuated trip hammers,

Referring now to Figures 1 to 6, inclusive, the transformer tank 1 contains the windings o! a transformer submerged in abody of oil 5. The interrupter I is mounted upon the insulators-8 and 9 through .suitable split clamp contacts 10 and I2, these contacts having clamping lugs such as l3l3,drawn together by bolts provided with clamping nuts I l-l4 to provide good electrical contact and solid mechanical support for the interrupter I. The insulators 8 and 9 carry the clamping contacts l0 and I2 and the insulators are, in turn, supported upon a suitable frame, which may be a channel member l5, disposed vertically at one side wall of the tank I. The contacting clamps l0 and I! are preferably formed electrically integral with connecting lugs lB-I 6, one of which may lead to the line connection and the other to the transformer winding.

The interrupter comprises an intermediate insulating sleeve H, which may be of bakelized fiber, or. glass, or any other suitable material, with metallic ferrules-such as l8l9 cemented, or otherwise bonded upon the ends of the sleeve. These ferrules are arranged to pass axially within the clamps l0 and I2 and be engaged mechanically and electrically by said clamp. g The ferrule i8 is provided with a reduced piloting portion at its lower end to assist in conducting the contacting portions of the ferrules into the correspondcontacts may obviously be arranged in any other suitable fashion for mechanically and electrically supporting the interrupter properly in position and connection. The upper ferrule I! (see particularly Figure 3) has an extension beyond the end of the sleeve I-I within which the upper contact 20 is supported. This extension 22 of the upper ferrule is threaded at its lower end to receive the insulating bushing 23 which, as will be pointed out later, provides an arc constricting passageway and a passageway for directing the flow of arc extinguishing fluid through the arc. The bushing 23 has a flange which is threaded to an internal thread 24 withinthe extension 22, and the said bushing is recessed to receive the lower end of the sleeve 25 of insulation. The sleeve 25 the said lower ferrule ll. An annular liquid director is supported upon a sleeve 34 which is slidably mounted on the rod 25. The junction of the rod 28 and the tip 25 provides a shoulder 55 which engages the sleeve 34 when the rod is drawn down by the spring 24. By this construction the rod and its arcing tip are first drawn down through the sleeve 25 and the bushing 25 before the liquid director 35 is picked up. 'Ihe liquid director 35 fits fairly closely within the lining sleeve 35 provided at the upper end of the main sleeve II. This lining sleeve 35 performs the, double function of first increasing the thickness of insulation to prevent puncture between the live parts within the sleeve ll and'the ferrule i9 outside of the same when interruption progresses to the point of creating a potential difference between the parts. The sleeve 35 further provides a removable liner which, if damaged by the arc, may be removed and replaced without the necessity of replacing the main sleeve II, which might otherwise be injured by the arc.

The upper end of the-ferrule extension 22 has communicating therewith an expansion and condensing chamber 31 which is closed off from atmosphere and communicates only with the upper end of the ferrule extension 22. Within the expansion and cooling chamber 31, the walls of which are preferably formed of metal throughout, although this is optional, there is disposed a mass of subdivided metal to form condensing and cooling means, this mass 3| preferably consisting of a large number of circular plates apertured at the center and clamped in spaced, parallel relation, upon a central mounting rod or sleeve. The rod upon which the plates 38 are mounted is preferably centrally located and is indicated at 39. To the lower end of the rod there is connected a spring contact member 20 consisting of a sleeve, the upper end of which is threaded upon the rod 38 and the lower end of which is slotted to provide a plurality of contact fingers extending below the lower end of the rod 35, these spring fingers being further reinforced by' a garter spring 2i, that is, a coil spring lying in a groove on the outer periphery of the spring fingers of the sleeve 40, and tending to constrict the same. The lower end of the rod 39, which lies within the sleeve 20 and above the tips of the spring fingers, constitutes an arcing tip 491:. It functions largely to centralize and position the spring fingers of the sleeve 20 and provides an arc terminus having sufficient section and surface during the circuit interrupting process. The upper end of the arcing tip 26 is preferably chamfered oil to correspond to the funnel-like socket formed by the spring fingers of the sleeve 20. The body of the interrupter is preferably provided with an arc extinguishingmaterial, herein shown as liquid, having suitable arc extinguishing and insulating properties, the the level of the liquid preferably being approximately at or below the bushing 23. The level of the liquid may be considerably varied, but it should be in such position as to act promptly upon the are as soon as the same is confined within the sleeve 25 and the bushing 23. For this purpose it may stand at approximately the top of the bushing 23. 7

We contemplate also the utilization of a solid arc extinguishing material instead of the liquid or, in fact, any suitable form of arc extinguishing material which will produce the desired effect hereafter described in connection with a statement of the operation of the present device,

Operation of the circuit interrupter The circuit interrupter thus far described, assuming that the movable and stationary contacts are in engagement and that current is being conducted through the device, will operate to interrupt the flow of current when the movable terminal is released and permitted to descend under theaction of the tension spring 80. As soon as descends, drawing the are into the restricting passageway of the sleeve 25 and the bushing 23, the metal vapor and ionized gases which may be contained within the are are driven longitudinally. upward into the condensing and cooling chamber 31, where they are out of the infiuence of the arc, and further fiow of arc extinguishing medium occurs. When the rodlilre member 28 has descended to the point where the shoulder 35 engages the sleeve 54, the liquid director 34 tends to descend and the liquid below the director is projected upwardly into the space where the arc is formed and maintained. The scavenging action of the flow of the gaseous medium endwise of the are through the restricted passageway which confines the arc laterally, and the increase in pressure of the said medium, is highly effective in extinguishing the arc and stopping the flow of current. Itis to be understood that the aforesaid scavenging action may be secured by the use of a solid are extinguishing material, which, under the heat of the arc, yields a gaseous medium for effecting the same purpose. The gaseous medium is driven up into the space I1, where it tends to be cooled and condensed.

The contraction of the spring 30 carries the arcing tip down into the liquid after current fiow ceases, further interposing a dielectric medium between the terminals.

The device is intended to be reset or reloaded in the shop or factory after a single operation, but we do not wish to confine the invention to that specific procedure. The employment of a completely closed unit in a situation such as herein illustrated is highly desirable, inasmuch as the products of the are or the arc extinguishing materials are not brought into contact with the insulating oil 5, and hence do not tend to contaminate the same, even by repeated operations.

The detent or clutch mechanism The movable rodlike member 28 is held in circuit-closing position, that is, in engagement with the stationary contact 20, by a clutch or detent which is formed in part by the sleeve 25.

The upper end of the rod 28 or the arcing tip 25 has a peripheral groove 4| which registers with a pair of diametrically disposed op'enings 4l4ll in the sleeve 25. The sleeve 25 is fiattened or slabbed off on opposite sides where the openings 40-40 are formed, and a holding member in the form of a yoke or U-shaped clamp 43 has its arms 44-44 overlying the fiat sides of the sleeve 25. The wall thickness of the sleeve 25 at the flattened portions and the diameter of the recesses 44'44'.which may bebrought into' register with the balls 42-42 by shifting of the fork or clamp member 43 to the left, therebyto release theclutch between the sleeve 25 and, the

I rod 26. Thus the member 43 constitutes a clutch releasing member, or a detent releasing mem- V ber for releasing the movable contact 26 to allow the springf36 to operate the device.

5 The normal position of the parts is shown in Figures 3 and 4, and it is to be understood that when the member 43 is moved to the-left, as

viewed in Figure 4, to the point where the recesses 44'-44' register with the openings 46-46, the balls42-42 will be driven out of the groove 4| by the tension of the spring 36 and can drop into the recesses 44'44, thereby allowing the arcing-tip 26'and associated parts to bereleased. This release member 43 is actuated by the power element P which I shall now describe. The power element P is controlled, directly or indirectly, by the thermostatic responsive element T which will be described later.

The powereZeme'nt A sidewall of the ferrule extension 22 is apertured transversely and threaded to receive. a threaded nipple or stud. The power element comprises a tubular cylindrical housing member 45 having an integral threaded neck portion 46 threaded into the opening in the side wall of the ferrule extension 22, as shown in Figs. 3 and 4. The opposite endof the barrel or tubular housing member 45 is formed with an open end which is closed by a cap member 41, threaded to the end of the barrel and sealed as by a gasket 48. The

central part of the head member 41 is provided with a threaded opening 49 through which is threaded the stem 56 of the thermally sensitive element T, Within the barrel 45there is provided a heavy coil spring 52 which is compressed between the head 41 and a spring follower 53. The spring follower has a tubular plunger 54 guided within the hollow neck 46. At its outer or left-hand end, as seen in Figures 3 and 4, this hollow plunger 54 has a reduced diameter. The reduced diameter portion and the main portion of the plunger 54 meet at an annular shoulder which, as shown in Figure 3, normally lies withm the neck 46. The outer end ofthe reduced portion of the plunger 54 extends through an opening in the release member 43, as indicated at 55, and the release member is held on the reduced portion 55 by a split ring or other means forming a shoulder upon the outer end of the reduced portion 55 beyond the fork of the release member 43. As herein shown, a groove is formed inthe outer periphery of the reduced portion 55 anda wire ring 56 is contracted into the groove to form a shoulder on said member 55. The outer end of the reduced member 55 is counterbored to provide a shoulder, as indicated at 51 in Figure 4, and a cross-pin 58, to which is connected a tension link 59, is seated in said counterbore 51 against the shoulder at the end of the same. This tension link 59 is preferably a thin, flat strip which extends through the hollow plunger 54 and has its rear end held by the anchorage provided by. amember providing a mechanical advantage,

this member being indicated by the reference letter M in Figures 3- to 6. The mechanical advantage device M anchors the tension link 59 to the head 41 of the barrel member 45 under the control of the thermostatically controlled element T, as will be described later.

The operation of the powerdevice is as follows: The compressed coil spring 52 contains a very considerable power which is applied to two purposes. link 59 fromthe restraint of the mechanical advantage device M and the thermally responsive The first purpose is to free the tension device T, as will be described later, and the sec- I ond function is to operate the clutch release device 43. The reduced diameter portion 55 of the plunger 54 is adapted to'slide freely in the hole through the release member 43, hence the spring 52 may expand and drive the follower 53 and plunger 54 to the left until the shoulder on said plunger 54 engages the release member 43, where- 7 41 is secured in fluid-tight fashion to the end of the barrel 45 by means of the interposed gasket held by the screw threads. The anchorage of the threaded stem 56 in the head 41 is rendered fluidtight by a conical shoulder 66 which seats in a conical seat and forms a tight closure, like a valve, sealing off the opening through the head 41. A hollow shield member 62 formed in the shape of a perforated cup or guard, has its bottom wall threaded onto the threaded stem 56 against the head member "and it protects the thermally responsive member T from mechanical injury while'permittingfree access of the surrounding medium. The thermally responsive device T and mechanical advantage device 'M for controlling the tension link 59, are built into a unit which is shown more clearly in Figures 5 and 6.

The mechanical advantage device and the thermally responsive device The body of the thermally responsive device and the mechanical advantage device comprises a. tubular stem 56 having a conical sealing surface 66, as heretofore described, for making a fluidtight joint. This conical surface 66 is formed upon an enlarged head member 63 on the opposite side of which extend two fiat ears 64-64. To

. the opposite sides of these two cars 64-64 a pair .of plates 65-65 are riveted, these plates being preferably of metal. The plates 65-65 are spaced apart by a block member 66 which is disposed substantially midway of the length of the plates 65. Registering slots 61 in each of the plates 65 extend from the left-hand end as viewed in Figures 5 and 6 to substantially the spacing block 66.

.This slot is to receive the tension link 59. A

mechanism obtains over the tension link II. The tension link is, is perfc-rated as indicated at I! (see Figure 6) and the levers, heretofore described, extend through this perforation. The tension link 59 bears upon the first lever 88 intermediate its pivot and its free end. The free end of the lever it rests upon the lever 69 adjacent the pivot point of the lever 69. In turn, the free end of the lever 69 rests upon the lever III adjacent its pivot point, and the lever 10 has its free end bearing upon the final lever I2 adjacent the pivot point of the latter. The final lever I2 is long enough to extend beyond the side plates. This lever 12 has its end slotted and pinched upon a high tensile strength wire of small diameter shown at H. A formed tubular guide member ll lies partly between the plates 85-65 and extends between the ears 64-64 and is lodged in an enlarged portion of the bore within the stem 50. Thus it forms a guide or conduit for the high tensile strength wire 14. This wire 14 is preferably a nlckel-chromium-iron alloy wire such as chromel or nichrome. The stem ill has a threaded part H which terminates in a neck l1 and has a cap or cover member 18 sealing the end of the bore through which the wire I4 passes. The end of the neck 11 and inside of the cap II are oppositely coned to provide space for a button of a thermally sensitive alloy. This alloy is of a character to melt at approximately C., that is, at a temperature below that at which the oil will form vapors or fumes which are ignitable.

The end of the fine wire H within the button 80 is formed into a hairpin turn, or hook, so as to anchor the wire therein. The alloy button 80 is preferably cast in place, but it may be preformed upon the wire and the wire then inserted through the bore 19 and the guiding tube 15, and the cap 18 is thereafter fastened in place upon the neck II to form a fluid-tight seal. The rim of the cap II is preferably seated into a groove, or fluid tightness may be secured merely by press fit. The alloy button 80, as above stated, is preferably cast in place, but it may be preformed, and provided with a slight neck to center the same suitably in the open end of the bore 19.

The alloy button 80 is confined under considerable pressure between the cap 18 and the end of the neck TI to bring these parts into good thermal contact. The button 80', while in good thermal contact with the cap 18 and the portion of the neck contained within the cap, is nevertheless thermally quite remote from the adjacent mechanical structure. The guard 62, which serves to protect the device from mechanical injury, is also directly supported in the oil, or other surrounding medium, and hence is fairly closely responsive to the temperature of the oil. However, it is thermally remote from the thermally sensitive element by the length of the interposed neck and the space between the barrel portion of the shield 62 and the cap I8. This button 80 is,-therefore, rapidly and closely responsive to temperature changes in the oil surrounding it.

The operations of the thermally responsive device and mechanical advantage device are as follows. The leverage system gives a mechanical advantage in the specific construction herein illustrated of approximately to 1, although it will be understood that this may be widely varied. The tension of the link 59 produced by the coil spring 52 tends, through the compound leverage system, to pull the wire ll out of the button" in which the end is anchored. The anchorage of the wire 14 in the button 80 by the hooked end is such, however, that the button of alloy It must completely soften before the wire will be pulled out of the same. Thus, to a large extent, the mere bonding between the wire and the button such as would be presented by mere surface contact, and the uncertainty of operation connected therewith, is avoided. Itlis desirable in the operation of the power device that the resistance of the tripping mechanism and the alloy button 80 be not additive. otherwise the calibration of the device might be effected by the wrong factor. It is for this reason that the plunger 54 has a lost motion connection with the trip or release member 43 so that the sole resistance to the initial expansion of the spring I! is the thermally sensitive device T, as exercised through the mechanical advantage device. The tension in the link It comes mechanically through the levers upon the plate 6! and from the plate 65 upon the head I! and the barrel head 41. Only a verysmall part of said tension (in the present case about ti th) comes upon the thermally sensitive device T. Assume that the oil in the transformer casing in which the thermally sensitive device T is immersed reaches a temperature which is that for which the ailoy'is designed to melt. Thereuponthe alloy melts and the hooked end of the wire I! is freed so that it may be drawn either through the bore 10 in hooked condition, or straightened out as it is drawn through the bore. This allows the lever 12 to swing in a counterclockwise direction as viewed in Figure 5. It will be observed that as the leverage system begins to move it loses its ratio of mechanical advantage quite rapidly. That is to say, as the levers begin to swing under the influence of the tension link 59, the free ends of the levers recede from the pivoted ends of the companion levers, thus reducing their ability to. resist the tension of the link it and finally swinging clear of the link 5! and allowing the same to pass on to the last lever II, which has merely the function of pulling the wire 1| through the bore of the guiding tube 15 to hold it. Therefore the initial motion of the spring 62 is devoted to insuring the release of the thermally sensitive device, and the succeeding motion of expansion of the spring 52 is devoted to the tripping or operating of the release member 43.

Obviously, the amount of preliminary motion to ensure rupture of the bond of the alloy may be increased or the total stroke may be increased or diminished, as desired. In Figure 4 we have indicated the part of the stroke devoted to the bond rupture of the thermally sensitive device and the part of the stroke devoted to tripping the cutout. The dimensions and proportions may obviously be varied.

After operation of the device, the clamping contacts Ill-i2 are released, and a new device is substituted by the operator. The actuating de vice is thereupon restored to working condition in the shop or factory by replacing any parts which may have been damaged by opening of the circuit or otherwise, supplying a new thermally sensitive button It and wire H, resetting the mechanical advantage device to tension link 59, the plunger 54 and the spring 52, closing the contacts of the interrupter and holding them by means of the clutch device, and supplying a suitable charge of arc extinguishing material.

Whereas, in the device just described. the interrupter with its thermal control and intermediate mechanism is mounted directly in the tank, the interrupter may advantageously be placed outside the tank and the thermally sensitive element,

with or without the power device, disposed in the tank in the oil through the temperature of which it is to be responsive. Thus, as shown in Figures 7 and 8, the interrupter I may be disposed in a separate tank, the temperature responsive device and the power element, which are disposed'in the transformer oil tank, being provided with a mechanical transmission, or other suitable form of transmission, to produce operation of the interrupter when the thermally sensitive device responds to a dangerous oil temperature.

Separated thermally responsive device and interrupter Referring now to Figures 7 and 8, the interrupter I is mounted in a pair of split champ contacts Ill-l2 which may be identical with those shown in Figures 1 and 2, the lower clamp contact l8 being mounted upon a suitable bracket member 82 which is connected at its lowerend to a conductor 83extending through the insulating bushing 84 leading to the outside of the auxiliary tank 4. The upper clamp contact i2 is mounted upon another bracket, such as 85, which also, in turn, is mounted upon a conductor 86 extending through an insulating bushing 81 in the wall of the main tank i. The conductor 86 is a hollow conductor providing a passageway through which extends a push rod 88 forming the mechanical transmission between the power element and the release element of the interrupter I. An electrical terminal 89 is connected to the end of the hollow conductor 86, this terminal 89 being adapted to be con'nectedto one of the transformer windmgs.

The brackets 85 and 82 are braced with respect to each other by a bar of insulating material such as 90 and the clamps l8 and I2 may also be braced with respect to each other by a similar bar of insulating material 92. These bars also form guides. to facilitate the introduction of the interrupting units within the clamp contacts 18 'and- I2 and to register the releasing mechanism of the interrupter with the push rod 88.

The interrupter, with its clutch and release members, is substantially identical with the corresponding mechanism described in connection with Figures 1 to 6. However, instead of threading the power unit stud directly into the opening in the side walls of the ferrule extension 22, the stud threaded neck is now aligned by a coupling sleeve 93 with the hollow conductor 86 so that the plunger 54 of the power element is now aligned and in operative relation to the push rod 88. The power element and thermally sensitive element are identical with the corresponding structures heretofore described. The releasing fork 43 is, in Figure 7, connected to a thrust rod 94 guided in the bore of a tubular member 95 which has a threaded neck 96 like the corresponding part of the barrel 45. This threaded neck 96 is threaded into the opening in the side wall of the ferrule extension 22 and the outer end of the rod 94 is registered with the push rod 88. The outer endof the rod 94 is sealed to the tubular member 95 by a corrugated bellows 91, of metal, one end of which is beaded and, if desired, soldered to the fitting 95 and the other end of which is secured to the end of the thrust rod 94. The thrust rod 94 preferably has a head or enlargement 98, with a spring 99 of suflicient strength only to hold the rod 94 and the release fork 43 in normal position. A plate I88 may cover the end of the push rod 94 for engagement by the end of the thrust rod 88. A suitable guard or housing I82 surrounds the metal bellows 91, this guard having a head I83 with a suitable aperture I84 through which the thrust rod 88 may project in operating the device.

The operation of this device is like that of the device of Figures 1 to 6 in all essential respects, as modified by the interposition of the transmission, and the necessity for sealing off the unit from the transmission. The fitting 95 is threaded A .in fluid-tight relation into the opening in the ferrule 22 and the flexible bellows 91 seals ofi the end of the rod 94 so that the interrupting unit is sealed fluid-tight. The guard I82 may act not only to protect the metallic bellows 91 from external injury, but also may limit the outward travel of the rod 94 to protect the bellows from overextension. Thus the temperature responsive element T, which is directly responsive to the oil temperature in the transformer tank, in turn releases the tension link of the power element P, and the power element, after first insuring breaking of the bond of the thermally responsive element, then proceeds to operate the thrust rod 88 and it, in turn, operates the corresponding rod 94 which is connected to the release fork 43. The remainder of the operation is as described in connection with the'operation of the interrupter unit heretofore recited. It is to be observed that there is a lost motion between the plunger 54 and the operating rod 88. Obviously, such lost motion may be interposed between the rod 88 and the plunger rod 94, but preferably lost motion is at the former location, so that the power element may first free itself from the bond of the thermally responsive means and then proceed to institute operation of the interrupter.

Remote control and yang operation This modification is illustrated in detail in Figures 9, l and 11. In this construction the thermally sensitive element T releases the power element P which exerts a pull upon the cable I and this trips a mechanical relay R for tripping the interrupters or cutouts I, one of which may be connected in each phase of a three phase circuit, for example, which is connected to a-three phase transformer.

There are three interrupters, one in each phase lead to the transformer windings. former windings are disposed upon a common core and in a single bath of oil, then a single thermally sensitive element T and power element F control the relay mechanism for tripping the interrupters in all three phases. If, however, the transformer bank comprises three single phase transformers, then a thermally sensitive element is placed in each of the transformer tanks and any one of the thermally sensitive elements, operating through the relay mechanism, is capable of opening the interrupters in all three phases.

One of the insulators 8 which supports the interrupters I is shown in elevation in Flgure 9. They are connected to a supporting, plate l which, in turn, is secured to the side wall of the tank 8. The insulator 8 has a pair of angularly' If the trans the bar III, and a further substantially vertical portion H3 the upper end of which is. connected electrically and mechanically to the split clamp contact I2.. The horizontal portion of the bracket II1 forms a perch or seat for an angular bear ing bracket H6, this bracket being formed of L- shaped plate of sheet stock having a base porticn and a vertical portion. The base portion is clamped to the bracket Ill and is thereby supported upon the insulator. The vertical part of the bracket II! is substantially rectangular, and it has a central opening providing a bearing for the bakelized shaft I22. This shaft is common to the three phases. Similar brackets IISA and H63 also provide bearing support for the shaft' I 22. Between the brackets II! and H63, an operating or reset handle I23 is provided. A flanged metal bearing collar I24 is fastened upon the shaft I22. The flanged bearing sleeve I24 is held upon the Bakelite shaft I22 by a pair of screws I26-I25 which screws also hold the ratchet collar I26 upon the said bearing sleeve I24. The collar I24 has a tooth I21 which is adapted to be engaged by the latch or detent I26 to hold the shaft I22 against rotation in a counter-clockwise direction as viewed in Figure 9. The latch or detent I26 is in the form of a bell crank pivotedat I26 upon the vertical part of the bracket H6. The free arm of the bell crank is pivoted on a pin I30 which is connected to the Bakelite link or rod I32. A retrieving spring I33 is connected between the actuating arm of the bell crank I26 and the base of the bracket H6. This spring thereby tends to hold the latch of the bell crank in position to be engaged by the tooth I21. When the rod or link I32 is pulled upwardly against the tension of the spring I33, the latch I26 is released from the detent I21, thereby releasing the shaft I22 for rotation in a counter-clockwise direction as viewed in Figure 9. A trip hammer I34, shown in detail in Figure 11, having a head or striker I35 and a hub I36, is mounted upon the bearing .sleeve I24. The hub I36 flts loosely upon the bearing sleeve I24 but is compelled to turn with the shaft I22 and bearing sleeve I24 by virtue of the screw pin I31 which extends through a slot I 36 in the hub member I36 and is secured to the bearing sleeve I26 on the shaft I22. Thus a small amount of angular play, as provided by the slot, is permissible between the trip hammer I34 and the operating shaft I22. The trip hammer I34 has a stop shoulder I39 which is adapted to engage a pin I secured in one corner of the vertical plate of the bracket H6. The head or striker I36 is aligned with the opening I04 of the casing I02 of the sealed release rod 94 which trips the interrupters I.

A coil spring I40, having one end engaging the bracket H9 and the other end engaging the trip hammer I34, is normally under stress tending to turn the shaft I22 in a counter-clockwise direction as viewed in Figure 9.

It can now be seen that by an upward pull on the rod or link I32 the bell crank latch I26 is swung out of engagement with the tooth I21, releasing the shaft I22 which, under the action of the spring, rotates the shaft counter-clockwise as viewed in Fig. 9, to cause the head or striker I35 of the trip hammer I 34 to engage the head of the rod 64 and this, in turn, pushes the release fork 43 to the left as viewed in Figure 4, thereby allowing the clutch balls 42 to drop into the recesses 44 and release the movable plunger rod of the interrupter to open the circuit. The spring may be reset by bringing the handle I23 'to the horizontal shaft I43,

in a clockwise direction as viewed in Figure 9 to bring the detent tooth I21 under the latch I26.

The shaft I22 bears three similar trip hammer mechanisms, as will be apparent from Figure 10. so that when the latch I26 releases the dog or tooth I21, the rotation of the shaft I22 permits each of the trip hammers to strike its corresponding clutch release mechanism and cause operation of all three interrupters. Each of the trip hammers I34 is provided with its individual spring and each trip hammer has a lost motion connection through a slot and pin I33-I31, shown and described particularly in connection with Figure 11. This permits the device to be assembled without requiring too great accuracy in angular alignment of the parts.

The link or rod I32 is pin Jointed at its upper end to an arm I46 through the pin or pintle I42. The inner end of the arm I40 is pinned or keyed which shaft is common to three control cables 1. The shaft I43 is supported in a pair of bearings I44I45 mounted at the ends of a bearing plate I46 which is, in turn, mounted upon the upper end of an angle bar I41, the upper end of which, as indicated at I43, may be flattened out into a common plane for providing a rigid frame or backbone between the frame I46 which supports the shaft I43 and the plate I6 (see Figure 9) which supports the insulators and, in turn, supports the shaft I22 and its mechanism. The angle bar I41 thus spaces the two operating shafts to maintain them in proper alignment and spacing, and it, in turn, is secured to the inside of the housing or casing 6. There are three operating arms I43I46-I49 for the three thermal control elements indicated in this construction, each of which is provided with a suitable clamp I60 for connecting to a corresponding cable 1. The clamps I50 comprise'a body portion I6I pivotaily connected to the end of the corresponding lever arm, a corresponding channel-shaped clamping member, and a pair of bolts provided with wing nuts for drawingthe parts I6I and I62 together. This clamp is provided in order to permit of suitable adjustment of tension of the cables 1. The cables 1 extend through conduits such as I53 to the individual transformer tanks, the conduits being bent to any desired configuration and being provided at their ends with clamping flanges I64 for attachment to corresponding bosses I56 on the tank 6. At their opposite ends the conduits or pipes I63 are cut off to the desired length and fastened as by means of a compression coupling I66 to the corresponding clamping flange I61 on the corresponding transformer housing I. The clamping flange I61 has a hollow stud I56 extending through a hole in the top of the transformer tank, that is, through the cover I69, a spool shaped button I60 being secured upon the end of the cable and, when the adjustment thereof with the extension of the cable is proper, the button I60 is drawn against the end of the boss I66. The thermally sensitive element T and the power element P are mounted upon the boss I66 and suitably connected to the button I60. The thermally sensitive element is constructed as shown in Figures'5 and 6. The stem 4615 extended through a flanged collar I62, a compression spring I63 bearing at its lower endagainst the flange of the collar I62, tending to throw the flanged collar and connected parts downwardly by the expansive force of the spring. A tubular sleeve I64 is secured to the collar I62 and extends upwardly through a fixed collar I 65 which collar is secured on the inside of a tubular frame member I66. The tubular frame member I66 is threaded at its upper end on the boss I56 for suitable mechanical support. 7

The sideplates 65 of the mechanical advantage device carry the compound lever system as described in connection with Figures and 6, held normally in place by the wire 14 and the alloy button 86, and these parts retain the tension link 59, the upper end of said tension link being anchored to the tubular support I66 by a cross pin I61 extending through the side walls of said tubular support I66. The upper end of the sleeve I64 is connected to a U-shaped tension member I66, the arms of which are connected to the upper end of the tube or sleeve I64 and the bottom of the U is apertured and has the stem I69 of the button member I60 extending loosely therethrough. An adjustable collar I16 is fastened on the lower end of the stem I69 to provide the lost motion desired for permitting the mechanical advantage device and the power spring to become. released by rupture of the bond in the fusible alloy before the load of tripping the mechanical relay device, which actuates the three interrupters, occurs. A suitable cushion or buffer I12 on the upper end of the collar I65 serves to stop the downward motion of the sleeve I64 and to take up the impact of the blow.

When the temperature of the oil 5 into which the thermally responsive device T dips, reaches a temperature which melts the alloy bond, the wire 14 which holds the lever system is released and the tension link 59, under the influence of the power spring I63, releases the lever system and hence the flanged collar I62, carrying the collar, the thermally sensitive device, and the side frames 65 with the lever system, downwardly, as viewed in Fig. 9. This pulls the sleeve I64 downwardly and it,'in turn, carries the U-shaped tension link I68 down on the stem I69 until the collar I10 is engaged, whereupon the power spring I63 exerts a pull upon the cable 1. The cable I, acting on the crank arm I49, turns the shaft I43 is a clockwise direction, as viewed in Figure 9, swinging with it the arm I46 and raising the rod or link I32. It is to be observed'that the pull on any one of the three cables is not influenced by the pull on any one of the other cables for the reason that when one cable 1 is ,pulled to the left, as viewed in Figure 9, the other cables merely slack their tension, and no interference results.

When the link I32 is'pulled upwardly the detent I28 is swung-out of the path of the dog or tooth I21 on the shaft I22 and the shaft I22, under the influence of the helical springs, is rotated in a counter-clockwise direction as viewed in Figure 9, throwing the hammers into engagement with the shafts or plungers 94 of the three interrupting units, thereby producing a simultaneous release of the movable plunger contact in each, with resultant interruption of the circuit and disconnection of the three phases from the transformer.

The power element shown in Figure 9 has the same two stages of motion described in connection with Figures 1 to 6, inclusive, so that the power element may free itself from the linkage and restraining effect of the levers and the-wire 14 before taking on the tripping function, in this case of the relay mechanism.

While 'we have shown the circuit interrupter as controlled by a thermally sensitive element,

it will be observed at once that the organization of parts, from the switch contacts back through the control mechanism to the thermally. sensitive button, is suitable for operation under the control of any other phenomenon. From beyond the sensitive button 86 to the circuit contacts, the entire organization of parts is useful of itself, and may be controlled by other control means, or even be under hand control. We do not therefore intend to limit the claims herein to thermal control, nor in fact to any specific control unless the same is specifically recited.

We do not intend to be limited to the details shown and described, except as the same are specified in the appended claims. We intend to cover all modifications which would occur to those skilled in the art, within the spirit and scope of our invention.

We claim:--

1. In a device of the class described, the combination of a switch having a movable switch member, latching means for holding said movable member in predetermined position, means tending to move said movable member, a normally stressed spring for disabling said latching means, means comprising a lever for holding said spring in stressed condition, and thermally sensitive means controlling said holding means comprising a tension strand connected at one end to said lever and a body of fusible alloy holding the other end of the tension strand.

2. As an article of manufacture, a completely enclosed switch unit, said unit comprising a main tubular housing, a pair of arcing terminals therein, one of the terminals being movable, a spring for moving said terminal longitudinally of the housing, a holding member having transversely movable release means extending laterally through a wall of said housing, and a supplemental housing joining the main housing and providing a fluid-tight closure for said release means.

3. In a device of the class described, the combination of a tubular housing open at one end, a recombining chamber communicating with said one end thereof, a stationary arcing terminal adjacent said one end, a movable rodlike arcing terminal normally in conductive relation to said stationary terminal, a transverse partition adjacent said one end, said partition having an opening through which said movable terminal projects, means to move the movable terminal, holding means for said movable terminal resting upon said partition, a release member movable transversely'of said movable terminal, and are extinguishing material in the housing in position to be acted upon by the arc formed upon separation of the terminals.

'4. In a device of the class described, the combination of a tubular closed housing, a stationary arcing terminal, a movable rodlike arcing terminal normally in conductive relation with said stationaryterminal, means to move the movable terminal away from the stationary terminal, a transverse partition having a tubular bore through which said rodlike terminal projectsand through which it is drawn upon separation of the arcing terminals, detent means for holding the movable terminal against movement, release means for said detent means, and are extinguishing material adapted to act upon the arc in said tubular bore.

5. In combination for use with a transformer having a casing,'a body of oil in the casing, and a winding in the oil, of an enclosed circuit breaker adapted to be connected in series with the transformer winding, a mass of fusible metal of low melting point adapted to be disposed in said body of oil, and mechanical trip means for the circuit breaker controlled by said mass of fusible metal.

6. In combination for use with a transformer having a casing, a body of oil in the casing, and a winding in the oil, of an enclosed circuit breaker adapted to be connected in series with the transformer winding, a mass of fusible metal of low melting point adapted to be disposed in said body of oil, mechanical trip means for the circuit breaker controlled by said mass of fusible metal, said circuit breaker comprising a tubular housing having external ferrules, and means adapted to be disposed outside the transformer for supporting the circuit breaker upon said ferrules.

7. In combination, a closed housing, a pair of separable contacts, a spring for separating the contacts, means for restraining said spring comprising a clutch within the housing, a rod for releasing said clutch extending through a wall of said housing, and metallic means for sealing said rod in fluid tight relation to said housing.

8. In combination, a tubular housing having a ferrule at each end, a stationary contact within one ferrule, a movable contact engaging the first contact, a spring between said movable contact and the other ferrule, a clutch for holding the movable contact, said one ferrule having an opening through the wall'thereof, and a clutch releasing member extending through said opening.

9. In combination, a tubular housing having a ferrule at each end, a stationary contact within one ferrule, a movable contact engaging the first contact, a spring between said movable contact and the other ferrule, a clutch for holding the movable contact, said one ferrule having an opening through the wall thereof, a clutch releasing member extending through said opening, arc extinguishing material in said housing, and

- a recombining chamber connected to the upper end of said ferrule.

10. In combination, a tubular sleeve having a metal ferrule at each end, an annular stationary contact in one ferrule, a transverse partition supported in said ferrule below said stationary contact, said partition having a passageway therethrough forming an arc confining bore, a clutch sleeve resting upon said partition, clutching means mounted in said sleeve, a rodlike terminal extending through said passageway and sleeve and being engageable by said clutching means to hold the rodlike terminal in engagement with the stationary terminal, a spring for said rodlike terminal, transversely movable release means cooperating with said clutching means, and means extending through the wall of the said one ferrule for operating said release means.

11. In a device of the class described, a sleeve of insulation, a ferrule on the upper end of the sleeve, a bushing of insulation secured in the ferrule adjacent said sleeve, a movable rodlike terminal projecting up through said bushing, said terminal having a groove, a stationary terminal, said movable terminal engaging said stationary terminal, a sleeve surrounding said rodlike terminal and resting on said bushing and guided thereby, said sleeve having openings therethrough, clutch bodies lying in said openings and extending into said groove, a yoke embracing said sleeve and holding said clutch bodies in said groove, means extending through a wall of the ferrule formoving said yoke to release said bodies,

and a spring for moving the movable terminal away from the stationary terminal.

12. In combination, a stationary contact, a movable contact, a spring for moving the movable contact, a detent for holding the movable contact against movement by the spring, a release member for releasing the detent, said release member having a 10st motion, a spring for moving said release member, a thermally releasable restraining element for restraining movement of said release member, the lost motion of said re lease element ensuring complete release of said release member from said restraining member before said release element releases the detent.

13. In combination, a movable member biased to move when released, a releasable detent means therefor for restraining the member against movement, a thermally responsive element comprising a thermally sensitive body which changes its consistency upon rise of temperature, a plunger biased for motion, a lost motion transmission operated by said plunger to release said detent and holding means for said plunger controlled by the condition of said thermally sensitive body.

14. In combination, a movable member biased to move when released, a releasable detent means therefor for restraining the member against movement, a thermally responsive element comprising a thermally sensitive body which changes its consistencyupon an elevation of temperature in response to externally applied heat and which is free from current flow therethrough, a plunger biased for motion, a mechanical relay means for releasing said detent, a lost motion transmission operated by said plunger for controlling said mechanical relay means, and holding means for said plunger controlled by the consistency of said thermally sensitive body.

15. In combination, a plurality of automatic circuit breakers, a corresponding plurality of releasable means for controlling the actuation of said circuit breakers, mechanical relay means for actuating said plurality of releasable means simultaneously, a thermally responsive element comprising a thermally sensitive body which changes its consistency upon elevation of temperature, said thermally responsive element being disposed in non-conducting relation with respect to current flow through said circuit breakers, a plunger biased for motion, said plunger by its movement controlling said mechanical relay means, and holding means for said plunger controlled by the consistency of said thermally sensitive body.

16. In combination, a thermally sensitive body of material the mechanical strength of which decreases upon the attainment of an elevated temperature in response to externally applied heat, means having relatively high thermal conductivity for sealing said thermally sensitive body from and rendering it quickly responsive to the ambient atmosphere, a lever restrained in controlling position by the body in its normal condition and adapted to be moved to non-controlling position, a tension link controlled by the lever, a power device restrained from action by the tension link, and a releasing member adapted to be actuated by the power device.

1'7. In combination, a thermally sensitive body of material of relatively light mass the mechanical strength of which decreases upon the attainment of an elevated temperature in response to externally applied heat, a lever restrained in controlling position by the body in its normal condition and adapted to be moved to non-controlling position, a tension link controlled by the lever, a power device restrained from action by the tension link, and a releasing member adapted to be actuated by the power device, said power device having two successive stages of action, the first stage of; action tending to move the lever to noncontrolling' position and the second stage of 'action tending to actuate the releasing member.

18. In combination, a thermally sensitive body of material the mechanical strength of which decreases upon the attainment of an elevated temperature, said body being diposed to be melted when the ambient temperature reaches approxtrolling member in one position and-being controlled by said plunger.

19. In combination, a spring barrel having a head, a spring actuated plunger extending out of the barrel, a spring between the head of the barrel and the plunger, a tension member connected to the plunger, a self-releasing detent connecting said member to said head, a tension strand controlling the self-releasing detent, and a' button of thermally controlled material disposed on the outside of said head and normally holding the tension strand against movement, said material being softened upon reaching an elevated temperature to release said strand.

20. In combination, a spring barrel havinga head, a spring actuated plunger extending out of the barrel, a spring between the head of the barrel and the plunger, a tension member connected to the plunger, a self-releasing detent connecting said member to said head, a tension strand controlling the self-releasing detent, a button of thermally controlled material disposed on the outside of said head and normally holding the tension strand against movement, said material being softened upon reaching an elevated temperature to release said strand, a shiftable member and a lost motion connection between said plunger and said shiftable member, said lost motion connection permitting said plunger to release itself from the control of the strand before encountering the resistance of the shiftable member.

21. In combination, a stressed coil spring, a plunger adapted to beactuated by the spring, a member for holding the plunger against the stress of the spring, a strand, a mass of material the strength of which is decreased upon attaining an elevated temperature for holding said strand, said mass of material being disposed to be melted when the ambient temperature reaches that at which destruction of the insulation of transformer windings begins and a mechanical advantage device providing a high ratio of mechanical advantage for said strand over said member, said ratio being rapidly reduced as said member moves when said strand is released by said material said device being disposed within said coil spring.

22. In combination, a stressed spring, a plunger adapted to be actuated by the spring, a member for holding the plunger against the stress of the spring, a strand, a mass of material the strength of which is decreased upon attaining an elevated temperature for holding said strand, said mass of material being disposed to be melted when the ambient temperature reaches that at which destruction of the insulation of transformer windings begins, a mechanical advantage device providing a high ratio of mechanical advantage for said strand over said member, said ratio being rapidly reduced as said member moves when said strand is released by said material, and means operated by said plunger only after predetermined motion of said member whereby the spring actuated plunger is substantially freed from the holding member before operating said last named means.

23. In combination, a rod having a recess therein, a stationary annular member embracing the rod and having an aperture registering with the recess, a holding body lying in the aperture and extending into the recess, a member for holding said body in said recess, said member being movable to a position to permit the body to move out of the recess to release the rod, a plunger for shifting said member to free the rod from the holding body, a spring for shifting the plunger, a link for holdingthe plunger against movement by the spring, and a body of fusible alloy for restraining the link.

24. In combination, a tubular sleeve of insulation having ferrule means at each end, the upper ferrule means having 'an extension of enlarged diameter at its upper end comprising a closed cooling chamber, switch contacts enclosed by the sleeve and ferrules, a laterally extending housing opening through the aforesaid ferrule extension of the upper ferrule, thermally sensitive means carried by said latter housing, and means subject to said thermally. sensitive means for controlling the operation of said switch contacts.

25. In combination, a tank adapted to contain a body of liquid, a non-conducting bushing extending through one wall of the tank, a hollow conductor extending through said bushing, a thrust rod extending through said hollow conductor, a thermally sensitive element supported on said hollow conductor within the liquid insaid tank, a plunger for operating said thrust rod controlled by said thermally sensitive element, a circuit interrupter having a closed housing comprising an insulating sleeve bearing external terminals in the shape of ferrules, means connecting the upper ferrule to said hollow conductor, terminal means connected to the lower ferrule, switch means withinsaid interrupter housing, a detent for the switch means, and releasing means for the detent means extending through the hous ing and registering with said thrust rod.

26. In combination, a tank adapted to contain a body of liquid, a non-conducting bushing extending through one wall of the tank, a hollow conductor extending through said bushing, a thrust rod extending through said hollow conductor, a thermally sensitive element supported on said hollow conductor within the liquid in said tank, a plunger for operating said thrust rod controlled by said thermally sensitive element, a circuit interrupter having a closed housing comprising an insulating sleeve bearing external terminals in the shape of ferrules, means connecting the upper ferrule to said hollow conductor, terminal means connected to the lower ferrule, switch means within said interrupter housing, a detent for the switch means, and releasing means for the detent means extending through the housing and registering with said thrust rod, and a metallic bellows for sealing said release means.

27. In combination with a tank adapted to contain a body of insulating liquid, a chamber formed on the outside wall of the tank, an insulating bushing extending between the chamber and the inside of the tank, a hollow conductor extending through the bushing, a circuit interrupter disposed in the chamber, said circuit interrupter comprising a closed tubular housing having contacts biased to'open, detent means for holding said contacts in conducting relation, trip means for releasing said detent, thermally controlled means, and a member controlled by said thermally sensitive means extending through said hollow conductor for operating said trip means.

28. In combination with a plurality of tanks. circuit conductors extending to each of said.

. tanks, thermally sensitive means in each of said tanks, a plurality of circuit breakers for controlling said circuit conductors, a common trip means for each of said circuit breakers, and transmision means between each of said thermally sensitive elements and said trip means.

29. In combination with a plurality of apparatus tanks, thermally sensitive elements in said tanks, a circuit interrupter tank containing a plurality of interrupters, one for each apparatus tank, each of said circuit interrupters having iniividual release means, a common actuating member for each of said release means, a trip member for said common actuating means, and means under control of each of said thermally sensitive elements for controlling said trip means.

30. In combination with a plurality of electrical circuit conductors, a corresponding plurality of circuit interrupters having individual trip means, thermally sensitive elements responsive to heat given oil by said conductors, a common actuating member for said trip means, a single detent for said common actuating'means, and a transmission from each of said thermally sensitive elements to said trip means including a plurality of flexible cables.

31. In combination, a plurality of circuit conductors, a corresponding plurality of circuit interrupters in series with said conductors, said circuit interrupters having individual trip means. a shaft provided with means for actuating said trip means simultaneously, spring means for actuating said shaft, a detent for holding said shaft against movement by said spring means, a thermally sensitive element responsive to heat given oil by said circuit conductors, a power unit for each thermally sensitive element, a second shaft, a connection between said second shaft and said detent for releasing said shaft to trip all of the circuit interrupters, and transmission means between said power unit and said second shaft comprising a flexible tension element.

32. As a means for opening an electrical power supply circuit upon the occurrence of predetermined thermal conditions in a body related to said circuit, the combination of a compact high duty circuit breaker comprising a pair of separate contacts provided with are extinguishing material and with operating means tending to separate said contacts, a detent holding said operating means from acting, actuating means for moving the detent to releasing position, and means comprising a body of fusible material for normally restraining said actuating means and adapted, upon attaining a predetermined temperature, to

release said actuating means to cause release of the detent and operation of the circuit breaker.

actuate the trip which holds the first spring, and

the first spring, in turn, operates the circuit breaker.

34. In combination a closed tubular housing, a stationary contact disposed therein adjacent one end thereof, means within said housing providing an arcing bore adjacent said stationary termine], a plunger having a contact at one end engaging said stationary contact, said plunger lying within said arcing bore and disposed wholly within said housing, a stressed spring connected to said plunger for retracting the same endwise of said bore, detent means within the housing for holding said plunger against the stress of said spring, release means for said detent means extending through a lateral wall of the housing, and are extinguishing material within the housing acting upon the are drawn in said bore to extinguish the same.

35. In combination a tubular sleeve of insulation having ferrules forming external terminals, a stationary switch terminal within and connected to one ferrule, a spring anchored to the other ferrule, a plunger disposed wholly within the housing having one end connected to the spring and the other end in engagement with said stationary contact, a releasable holding device for holding the plunger, said device being supported by said one ferrule, and a release member for said device extending through a lateral opening in the said one ferrule.

36. In combination for use with a transformer having a casing, a body of oil in the casing, and a winding in the oil, a circuit breaker having contacts adapted to be connected in series with the transformer winding, a housing for said circuit breaker, a mass of fusible metal of low melting point adapted to be disposed in said body of oil out of current conducting relation with respect to said contacts, mechanical trip means controlled by said mass of fusible metal for releasing said contacts for movement to the open position, and liquid arc extinguishing material in said housing adapted to react with the are formed between said contacts on separation for assisting in extinguishing it.

37. In a device of the class described, the combination of a tubular housing open at the top end. a recombining chamber communicating with said top end, a stationary arcing terminal adjacent said top end, a movable rodlike arcing terminal normally in contact engagement with said stationary terminal, a transverse partition underneath said stationary terminal having an opening through which said movable terminal projects, means for biasing said terminals apart, a release member for said movable terminal movable transversely relative thereto, a body of arc extinguishing liquid in the lower portion of said housing, and a liquid director slidably mounted on said arcing terminal and movable therewith after a predetermined movement thereof for directing said liquid in position to be acted upon by the arc formed upon separation of the terminals.

38. In a device of the class described, the combination of a tubular closed housing, a stationary arcing terminal, a movable rodlike arcing terminal normally in conductive relation with said stationary terminal, means to move the movable I tinguishing material in said housing adapted to react with the are formed between said terminals on separation thereof for assisting in extinguishing it.

39. In combination a fluid tight tubular housing, a stationary contact member disposed therein adjacent one end thereof, a movable contact member disposed wholly within said housing for engaging said stationary contact member, a tension spring disposed within said housing for biasing said movable contact member away from said stationary contact member, detent means within said housing for holding said contact members in engagement, release means for said detent means extending through a lateral wall of saidhousing, and bellows means surrounding said release means and secured in fluid tight relation to said housing for maintaining the fluid tight integrity of said housing and permitting operation of said release means by an externally applied force.

40. For combination with a plurality of circuits disposed to connect a load device to a current source, a circuit interrupter of the single shot blast type interposed in each of said circuits, a fluid tight housing for individually enclosing each of said circuit interrupters, externally operable tripping means, sealed in each of said housings for tripping the circuit interrupters enclosed thereby, fault responsive means individual to each of said conductors, and means responsive to the operation of any one of said fault responsive means for simultaneously operating all of said tripping means to completely disconnect said load device from said current source.

41. For combination with a plurality of circuits disposed to connect a load device to a current source; a shelf contained circuit interrupter interposed in each of said conductors comprising a pair of separable contact members disposed on separation to draw an arc therebetween, are extinguishing material disposed to form a blast for extinguishing said are, and externally operable tripping means for normally holding said contact members in engagement, the contact members of each circuit interrupter being mechanically independent of the contact members of any other circut interrupter; fault responsive means individual to each of said conductors, and means responsive to the operation of any one of said fault responsive means for simultaneously operating all, of said tripping means to completely disconnect said load device from said current source.

HUGH A. TRIPLE'I'I. SIGURD I. LINDELL. 

